1. Field of the Invention
This invention relates to a resin concrete composition particularly suitable for use as thick molded articles and excellent in low temperature curability, the main ingredients of which are an unsaturated polyester resin having allyl ether group and an aggregate. When the term "resin concrete" is simply used herein, it means to cover both resin mortar and resin concrete.
2. Description of the Prior Art
Hitherto, resin mortars and resin concretes of unsaturated polyester or the like have been used in various fields because of their superiority in mechanical strength and chemical properties to inorganic type concretes. However, their use is limited owing to cracks caused by the shrinkage and heat evolution at the time of cure, the deterioration of physical properties caused by the incomplete adhesion to aggregate and the incomplete cure at low temperatures. Otherwise, these problems are solved at the sacrifice of the excellent characteristic properties which they originally have.
With regard to the prevention of crack, a few proposals have been made hitherto. One of the proposals is addition of a thermoplastic resin to the unsaturated polyester resin or the like. In this case, the thermal expansion of said thermoplastic resin due to heat evaluation at the time of cure is utilized to make the shrinkage low. Another proposal is to increase the elongation of resin. However, the addition of thermoplastic resin is undesirable because it increases the viscosity of resin, injures the workability of resin and deteriorates the mechanical properties of resin. In addition, in the case of large-sized molded articles, the local generation of heat sometimes causes sudden boiling of crosslinking agent, etc. and results in cracks. On the other hand, an increase in elongation of resin is accompanied by deterioration in mechanical strength, creep characteristics and chemical properties, so that the second proposal is considerably limited in application.
With regard to the enhancement of adhesion to aggregate, there have been proposed use of silane coupling agent and treatment with resin acid. However, they are unemployable from the economical point of view because of the high costs of operation and agent.
With regard to the incomplete cure at low temperatures, it is made possible to complete the curing by using a large amount of a curing catalyst or using a catalyst for low temperature. However, these are undesirable because they deteriorate mechanical strengths.
In view of the situations mentioned above, the present inventors have earnestly conducted studies with the aim of discovering a resin composition for use in resin mortar or resin concrete excellent in adhesion to aggregate, insusceptible to crack formation and excellent in low temperature curability. As a result, it has been found that a combination of an allyl ether-modified unsaturated polyester, an ethylenically unsaturated monomer and an aggregate is effective.
It is, therefore, an object of this invention to provide a resin concrete composition free from the above-mentioned disadvantages.
Other objects and advantages of this invention will become apparent from the following description.